The goal of this article is to determine the declaratory accounting core that makes it possible to find out what is the state of solvency of companies in the textile industry listed in the Stock Exchange of São Paulo (Bovespa). This is done by analyzing the financial statements through indexes and applying the Rough Sets Theory. The methodology used in the study is descriptive, based on documentary research and a predominantly quantitative approach. The survey was done using the indices of financial statements of the 21 companies of the textile industry listed in Bovespa in the period from 2002 to 2006. On the basis of the categorization of four classes, it became clear that the core of the declaratory accounting is made up of the following indices: liquidity drought, debt, financial dependence, stock flow, average collection period, average time of payment, return on equity and return on assets. Therefore, it is not necessary to review the twelve indexes initially used in this study to reach the conclusion that a company is solvent or insolvent; it is necessary to consider only the nine indexes that make up the declaratory accounting core.Key words: financial statements analysis, indices, solvency, declaratory accounting core, Rough Sets Theory.